Switch



swrrcn Filed April 6, 1942 2 sheets-sheet ZIT Zfl.

INVENTOR. A11/aart" B aait...

Patented Mar. 20, 1945 SWITCH Albert E. Baak, Minneapolis, Minn.,assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn.,a corporation of Delaware Application April 6, 1942, Serial No. 437,863

29 Claims. `(Cl. 175-375) The purpose of this invention is to provide acompact and simple switching device operable by various conditionresponsive means and readily adjustable for operation over a wide .rangeof conditions for adaptation to a variety of uses.

It is a further purpose of the invention to promay be further employedfor a control purpose, or for the same purpose, in a circuit ofrelatively large power and load requirements by the selection of ahousing section that includes therein a relay and the main switchingmeans for operation by the relay under the control of the switchcontacts of the main housing section.

Another object of the invention is the provision of condition responsiveswitching units that may obviously be adapted for operation in responseto one or more of a plurality of conditions which, for example, mayinclude pressures and temperatures. Thus, the pressure responsiveswitches illustrated and described belov might obviously be operateddirectly by temperature responsive means of the hydraulic type employinga, volatile fill, and it will be noted that the controlled by separateswitching means located l inthe device.

A particular object of the invention is the provision of a switch havingseparate housing sections that are adjustable with respect to each otherfor the ready and accurate adjustment of the switch for operation at aselected and prefor locking the housing sections in the selectedposition of adjustment to insure the proper functioning of the switchwhen subjected to considerable vibration.

One purpose of the invention is the provision of a switch for use withaircraft and motor operated devices wherein va main switch housingsection for a portion of the switch structure cooperates with aplurality of interchangeable switch housing sections which maybeemployed t0 vary the operating characteristics of the switch andadapt'the switch to a variety of uses with circuits havingwidely varyingpower arid load requirements. v In accordance with my invention a switchis provided which, for example,4 may be employed to operate a signal andthe switch contactsof the main housing section of the switch are readilyadapted to function directly for this purpose. 'I'he switch adapted tobe connected in a circuit for this purpose is provided with one of theinterchangeable upper housing sections of the type required by theparticular circuit and this housing section cooperates'with the mainhousing section with which it is adjustable -for controlling theoperation of the switch. The switch 4of pressure and temperature. vbeobvious that my differential pressure type of differential type ofswitch illustrated may further be actuated in response to a combinationIt will likewise switch may be employed for direct response to acondition by the use of a plug for the passage means communicating withone of the two diaphragm separated pressure chambers of the 4 switch.'

Other objects and advantages of my invention will become apparent fromthe detailed description of the illustrated examples disclosed in thedrawings and from a consideration of the aping the switch housinglocking means,

Figure 3 is'a vertical View partly schematic and partly in section of aswitch employing an upper housing section which includes a relayvand amodiiication of my switch embodying a pressure actuated reverse actingswitch unit, and

Figure 6 is a vertical view partly in section of a modification of myswitch embodying s. pressure actuated direct acting switch unit.

'In Figure 1 of the drawings, I have illustrated vmy differentialpressure reverse acting type of switch having a base portion 5 with apassageway 6 extending therethrough for connecting iiuid pressure.

with a rst source of duid pressure and a second passageway 'F extendinginto the threaded passageway 8 for connection with a second source ofThe base member 5 is provided with an externally threaded position t forreadily mounting the switch with respect to a duid pressure line. Athreaded plug member, not shown, may be threadedly inserted in thepassageway 8 if operation of this switch in direct response to thepressure admitted to the passageway 6 is desired. The base member 5 hasformed therein a chamber Il@ of relatively large transversecross-sectional area and shallow longitudinal depth, and the passageway@communicates with the lower portion of this chamber ifi.' A housingmember l 2 is separated from the housing member 5 by a diaphragm i3. Thehousing member i2 has formed therein a chamber il of relatively smaller*transverse cross-section which is separated from the chamber l by thediaphragm i3. The passageway i' in the base me1nber communicates throughan opening i9 in the diaphragm i3 with passage means d and H Y extendingthrough the housing member l2 for communication with the upper sidaofthe chainber iii. An insulating plunger member l5 of substantially thesame size as the chamber id is supported upon the diaphragm and mountedWithin the chamber it for slidable axial movement in response to changein the diierlence between the pressure which is exerted directly on theplunger from the chamber id and the pressure transmitted from chamberiii by operation oi` the diaphragm i3. It will be noted that thechambers il! and l, respectively, limit the movement of both the plungerib and the diaphragm i3. Because of the limited movement` to which theplunger and diaphragm may be subjected it is impossible to rupture orinjure the diaphragm by reason of the occurrence of excessive pressuresin either the passageway S or the passagemeans 8.

Extending through a passage in the housing member ,l2 is a stem 2d ofinsulating material which is associated with the plunger member I6 andaxially slidable thereby. A stationary switch contact member 2! is alsoassociated with the base member .i2 and forms a grounded connectiontherewith. An insulating member 21 serves to support a snap disk element28 with which is associated a movable contact member 3U. It will benoted that upon one sideof the snap disk the movable contact member isactuated by the plunger stem 20. A current carrying spring member 32 anda current carrying spring guide disk 33 cooperate with the f movablecontact member 30 on the other side of the snap diskiand serve to biasthe movable contact in opposition to the operation oi the movablecontact by the plunger operated stem 20. A mounting member 35 issupported by the insulating member '21 and an insulating member 36 forsealingly engaging the open end of Aa bellows member 3B which houses themovable switch contact biasing spring means.

A lower casing member I2 is threadedly mounted by the cooperating threadmembers Il upon an intermediate casing member I3 and serves to supportthe lower housing member 5 and the diaphragm 'I3 on the base member I2.An upper casing member I5 is threadedly secured by the cooperatingthread members II to vthe intermediate casing member I3. Various tationsto which the switching unit may be employed, as is more fully explainedbelow. The upper casing member I5 is at least in part formed by aninsulating plate 45 which serves as the support for a connector'pin 47.The connector pin il extends from a contact carrying base portion fitthrough the insulating plate and into an outwardly threaded hub formedby the casing member d5. Base portion i8 is removably received in andmakes electrical contact with a depression 49 in lthe closed end 5G ofbellows 3a.

The single connector element of the upper casing member illustrated inFigure 1 is incorported in a circuit which includes the connectorelement lli, the closed end of bellows 3B, the current carrying biasingspring 32, and the spring guide disk to the movable contact Sil. Whenthe diierential in pressure exerted upon the'plunger is such as topermit the stem 2@ to recede to a position adjacent the stationaryswitch contact, the snap disk will operate to rapidly close the movableswitch contact upon the stationarycontact which is grounded to thehousing member i2 'for completion of the circuit. Upon an increase indiierential pressure in the :duid pressure chambers i@ and ill a forceis exerted by the plunger and stem 2B upon the biased movable switchcontact and this force actuates the snap disk to rapidly open the switchcontacts.

It will be noted that this switch unit of my invention .may beconstructed for use with a circuit of a type requiring two separateconnector elements 17. Thus the second connector may be 40 justment ofeither the differential pressures or creasing or decreasing the tensionin spring member 32. In this manner the diierential pressure or thedirect pressures required for actuation of the switch contacts may bevaried to provide a wide range of voperation for the switch.

The lower and'upper casing members d2 and I5, respectively, have milledor formed on the outer side surfaces thereof teeth 52 which extendaxially of the switch. A sleeve member 5I is provided having teethmembers 55 internally formed thereon and extending axially of the sleevefor cooperation with the teeth 52 on the switch housing members. Thissleeve member 5I serves to lock and maintain the members in thepositions to which they are adjusted to insure proper operation of theswitch.

A passageway 51 is drilled, or otherwise formed, as best illustrated inFigure 2, through the sleeve vmember 5I and a passageway 58 is formed inthe mediate casing member. A split ring wire member B0 is mounted in theslot 58 and is bent at one end thereof-'to provide a pin member 6I andhousing members'and to prevent the sleeve Y member 54 from being axiallydisplaced from the switch as a result of vibration. To remove the sleeveit is merely necessary to iirst move the pin against the force ofthering biasing means passageway 58 prior to the engagement ofthecooperating 'teeth 52 and 55 of the housing and sleeve members. The pinis then depressed and the sleeve guided thereover until the pin engagesthe passageway 51 for locking the housing members in the selectedposition of adjustment.

Figure 3 discloses the actuating mechanism illustrated in Figure 1adapted for use in a switch when two connector elements are necessaryand where the main switch contacts are required to operate at power andload requirements that would prove prohibitive for the switch unitillustrated in Figure l. To adapt vthe mechanism of Figure l for thisuse an upper casing ,member isprovided that houses a relay 12, a set ofmain switch contacts including movable contacts 13 together withstationary contacts 14 and 15 and two circuit connector elements. Uppercasing -member 18 is interchangeable with member- 45 of Figure 1, andaccordingly a description of the member v18 will suffice for anunderstanding of the construction of the switch.

The upper casing member 18 has molded therein two insulating platemembers 11 and 18 through which two connector members 80 and 8| aremounted and supported. The connector members are at one end .secured tospaced and insulated conducting'plates or strap members 82 and 83,respectively, rst ends of which are mounted between the insulatingplates 11 and 18, the other ends of the connectors extending into thethreaded external receptacle portion of the switch cover. The strapmembers 82 and 83 are connected at their rst ends to the stationary 1switch contacts 14 and 15 respectively. v

The relay unit 12 is mounted upon an insulating plate member 84 and theentire unit is supported in the casing' 18 by a press t. A conductingplate member 85 is riveted to the insulating plate member 84 andsecuredto this conducting plate is a contact base member 86-which correspondsto the base member 48 of the switch cover unit 45 illustrated inFigure 1. The conducting plate 85 is connected by a lead 81 to aterminal of the relay windings 88. A second terminal of the relaywindings. is connected by a lead 88 to the strap83 which is secured tothe stationary switch contact 14 and the circuit connector 8|. The relayarmature member 88 is biased to the position illustrated in Figure 3 bythe spring biasing means 3| and rapidly assumes this position when therelay is deenergized. The connected movable contacts 13 of the mainswitch are secured by a bracket member 82 to the armature 90 for therapid operation thereof by the relay when the switch contacts 2| and 38located in the Ymain housing section of the switch unit are closed byoperation 'of the relay in response to the occurrence of a predeterminedpressure dierential, or of a predetermined pressure, for which theswitch has been adjusted. 1

Upon closure of the switch contacts 2| .and 38, located in the mainhousing section of the switch, a circuit is established from the switchlconnector element 8| through the strap member 83, lead 88, relaywinding 88, lead 81, conducting plate 85, conducting base member 86, thebellows and the current carrying spring biasing means 32, movable switchcontact 30 and stationary contact 2| located in the main housing unit tothe ground connection established thereby within the switch casing. Uponenergization of the relay winding 88 the 'armature 88 is actuated in amanner to rapidly close the main switch con-A tacts 13.' 'I'he closureof the main switch contacts 13 establishes a parallel circuit which in-`cludes the switch connector element 8|, strap member 83, stationaryswitch contact 14, m'ovable contacts 13 and stationary contact 15 of themain switch, strap member 82, and the associated switch connectingmember. 88.

Figure 4 relates to a modiication of the switch illustrated in Figure l,and has particular reference to the provision of a switching unit thatis directly responsive to pressure and of a modified switch base andunit supporting means. In this embodiment of the invention a base member|00 is substituted for the base member 5 illustrated in Figure l. A pipemember |8| having the externally threaded end portions |82 is threadedlymounted in the base member |88. 'I'his connecting line for the admissionof the fluid the pressure of which is employed to actuate the switchcommunicates with the passage |86 and the iiuid pressure chamber ||0.The upper base member ||2 having the chamber ||4' formed therein and.the diaphragm member ||3 are clamped to the ber by the screw and lockwasher members |||iy and I1, respectively. The bracket member ||5engages with a flange or ring member |8 secured in the lower switchhousing member for the purpose of mounting the switch in the properposition with respect to the lower base member |00. The entire unit maybe secured to a desired mounting bracket member by the screws or throughbolt members I.

The plunger, H6 mounted in the chamber ||4 is directly actuated by thepressure transmitted thereto from the pressure chamber ||0. In thisembodiment of the invention the bellows member |38 has openings |39formed in its end portion to bring about equilibrium between thepressure in the bellows and the varying ambient pressures resulting fromchanges in altitude to which the unit is subjected. It is apparent thatthis switch otherwise embodies the feature of construction described inFigure 1 of the drawings and accordingly further description thereof isnot necessary.

The switch unit illustrated in Figure 5 is of the direct pressureresponsive and reverse acting type and is a modification of the switchunit illustratyed in Figure 1. The reference characters applied readilyserve to identify the corresponding elements of the unit illustrated inFigure 1 and described above.

a chamber 2|0v of relatively large transversev cross-section and shallowlongitudinal depth which is bored or formed in the upper surface n ofthe base member. A housing member 2|2 has bored in the lower surfacethereof an annular member, or chamber, 2|4 which is of smallertransverse cross sectional area than the chamber 2| 0. A diaphragm 2|3supported between the lower and intermediate base members separates thechambers 2||l and 2|4. A plunger member `2||S of substantially the samesize as the chamber 2|4 and of insulating material is supported upon thediaphragm 2|3 for a slidable axial movement within the chamber 2|4 as aresult of the force transmitted thereto by the diaphragm upon variationof the fiuid pressure in the chamber 21u.

A passageway 2|5 extends from the chamber Zld of the base member 2|2 tothe upper surface thereof and secured to the chamber within thispassageway as by a roller projection, are a tubular insulating member2|? and a conducting sleeve member 2|8. A stem 226 associated withplunger Zl for movement thereby is slidably movable within theinsulating member 2| l. A stationary switch Contact 22| is mounted onthe upper end of the conducting sleeve member 2|8 and the stem 22|! isassociated with a switch contact 230 that is movable in alignment forcooperation with the stationary contact. The nievable switch contact isassociated on the upper side thereof with a current carrying springguide disk 233 which transmits pressure to the movable contact from -acurrent carrying spring biasing element 232.

A lower casing member 242 cooperates with the housing member 2|2 byoperation of the cooperating thread members 24| for clamping the basemember 205 and the diaphragm 2|3 against; the lower surface of thehousing member 2|2. The

upper casing member 245 likewise cooperates l with the housing member2|2 to which it is adjustably secured by the screw threads 244. Theupper casing member has formed therein a plate of insulating material246 through which a circuit connector element is mounted for support.

vOne end of the connector 241 supports a conducting plate and springguide member 248 against the insulating plate 246; The other end of theconnector is centrally disposed Within the circuit receptacle' formed bythe outer portion of 'the-upper casing member 245 and this receptaclehas the threads 249 formed on the outer surface thereof.

The' conducting plate 248 mounted in the upper casing member serves as abase for supporting the current carrying spring which serves to bias themovable switch contact to the contact closing position. The biasingspring ythus opposes the operation of the plunger and stem in theactuation of the movable switch contact in response to the pressure ofthe uid in chamber the pin cooperates with the passages 251 and 258drilled through the sleeve and housing members for locking the sleeve254 and casing members in any desired position of adjustment.

Upon av decrease in the pressure of the uid in the chamber 2| theplunger and stem are actuated downwardly under the bias o f the currentcarrying spring and the movable switch contact 23|) is seated upon thestationary contact 22 I. A circuit is then established which includesthe connector 247, plate 243, biasing spring 232, movable switch contact23|l, stationary switch contact 22| and the sleeve member 2|8 which isgrounded to the switch base member 2 I 2. When the iiuid pressure inchamber 2|@ increases sufficiently the plunger and stem actuate themovable switch contact to open the circuit.

TheJdiaphragm will withstand the actiony of very large pressures withoutrupture as a result of support received from the plunger when theplunger is actuatedto the position in which it is seated in and againstthe chamber 2|il.

The modineanon of my switch .unit illustrated in Figure 6 of the drawingrelates to a unit of the type illustrated in Figure except that theswitch is actuated upon a rise in pressure to a predetermined andselected value. 3|3 is subjected to the pressure exerted by uid admittedto the chamber 3H) for actuating th 2| (l.4 The upper casing member 245is longitudinally adjustable with respect to the housing member 2|2I byprovision of the cooperating The adjustment of the thread members 244.covering and housing member provides for varying the pressure exertedbythe switch contact spring biasing means to selectively vary theactuation of the switch throughout a wide'operat-v ing range.

The switch is maintained in a selected pqsition of adjustment bycooperation o f the sleeve mem'- ber 254 with the casing members 245 and242. Thus, the casing members have external teeth 252 formed thereon andthese 'teeth extending longitudinally of the switch for cooperation withsimilar teeth 255 formed internally on the sleeve member as describedwith respect to .the switch illustrated in Figure 1. Similarly, a splitring wire biasing'\member and 'pin 26| is mounted ina. slot 258 formedin the base member 2l|2 and plunger 3|6. The plunger 3|6 of insulatingmaterial has mounted therein the stem 32d. The stem is formed ofconducting material and is slidably movable within the insulating sleevemember 3|'| for contact with the conducting cup member 333 which guidesand is acted upon by the current carrying spring vbiasing means. Astationary switch contact 32| is supported by and grounded to the basemember 2| 2` at the inner surface of the chamber 3|4 in which theplunger is mounted. A movable switch contact 330 is mounted on the stem320 and is also movable within the chamber 3|4. Upon a suiiicient.increase in pressure in the chamber 3||l the diaphragm actuates theplunger and stem member to the elevated position in which the movablecontact 330 is closed with the grounded station- Vary contact 32|. Acircuit through the switch unit is then completed which includes theunit connector element, current carrying biasing spring, bias springguide member 333, stem 320, movablecontact 330 andthe stationary switchContact 32| which is in the switch base.

It will be obvious that the switching units of my invention may bedesigned for use with base' supporting and mounting members ofvariousshapes for cooperation with the variet/y ofmembers, such asaircraft engines and mounting panels, with which the units may beassociated.

From the above description it is apparent that in accordance with my'invention both the related and interchangeable members o f the switchingunits involve relatively -few parts which are of simple construction andthat by 'reason of the wide and selective range of adjustment providedthereby these switching units may be readily manufactured and assembledfor application in awide range of operating services. The compact switchunits 'are particularly adapted foruse.

with aircraft in the operation of. alarm, indicatving or controlcircuits which,.for example, may

. be directly responsive to fuel and oil pressures or may be responsiveto a diiference between carburetor air pressure, which is maintainedconstant Thus the diaphragm grounded contact with the switch contactcontrolling plunger for actua- 4 tion of the switch.

vention is to be dened .bythe scope of the appended claims. i

I claim as my invention:

1. A switch in combination comprising, a rst member having a passagewayextending through the member for communication with a rst pressurechamber of relatively large cross-section and shallow depth formed inone end thereof, a second member having a second pressure chamber formedin one end thereof and of smaller cross-section than the rst chamber, aplunger `of substantially the size of said second chamber and having astem mounted for movement within the second member, passage meansthrough said second member for communication with the second pressurechamber and including an open- .ing adjacent theinner side lof saidchamber, a diaphragm separating said'first and second pressure chambers,the depth of the chambers being.

such as to limit the movement of the plunger and diaphragm, stationarycontact'means associated with said second member, movable switch contactmeans, means including a snap disk, current carrying biasingY means andsaid plunger stem for actuating the movable Contact means, a bellowsenclosing the said biasing and switch contact means, a switch casingmember and an insulating member therein, electrical switch connectingmeans supported by the insulating member for connection with the currentcarrying biasing means and the said movable contact, and means includingsaid passage means for connecting each of said chambers with separatesources of fluid pressure for operation of the switch member in responseto the difference between the two separfate pressures.

V 2. A switch in combination comprising, a firstv member having apassageway extending through the member for communication with a firstpressure chamber of relatively large cross-section formed in'one endthereof, a second member having ar second pressure chamber formed in oneend thereof and of smaller, cross-section than the lirst chamber, a;plunger of substantially the size of said second chamber and having astem mounted forV movement within the second memb er, passage meansthrough said second member for communication with the second pressurechamber and including an opening adjacent the inner side of saidplunger, a diaphragm separating the two-said pressure chambers, thedepth of the chambers being such as to limit the move'- ment of theplunger and diaphragm, stationary contact means, movable switch contactmeans and means including a snap disk, current carrying biasing meansand said plunger stem for actuating the movable contact means, a bellowsenclosing said biasing and switch contact means, a switch casing memberand an insulating member therein, electrical switch connecting meanssupported by the insulating member and cong nected to the bellows forconnection with the current carrying biasing means and the said movablecontact, and means for associating the pas-l 3. A switch in combinationcomprising, a first member having a passageway extending through themember for communication with a rst pressure chamber of relatively largeVcross-section formed in one end thereof, a second member having achamber formed in one end thereof of smaller cross-section than the saidrst chamber, a plunger of substantially the size of Vsaid second chamberand having a stem mounted for movement within the chamber and secondmember, a

' diaphragm separating the two said pressure chambers, the depth of thechambers being such as to limit the movement of the plunger anddiaphragm regardless of the pressure applied thereto, stationary contactmeans, movable switch contact means and snap acting means for theactuation thereof, current carrying biasing means associated with thesnap acting means for opposing the operation of the movable switchcontactv by the said plunger stem, a bellows insulated from andcooperating with said second member for enclosing said biasing andswitch contact means,

' a switch casing member having an insulating vmember therein, andelectrical switch connecting means supported by said housing insulatingmember for switch actuated connection with the bellows, the currentcarrying biasing means and the said stationary and movable switchcontact means.

4. In combination comprising, a portion hav,

y exerted on one side thereof by the diaphragm and on the other side-bypressure from the second chamber, a stationary switch contact associatedwith said portion, a movable switch contact, a

member actuated by the plunger and extending through said portion foroperation of the said movable contact, means opposing the operation Y ofthe movable switch by the plunger including a sage means communicatingwith the first and snap acting means, and current carrying springbiasing means, a housing means for the spring biasing means, a casingincluding an insulated portion, switch connector means supported by andextending through the insulated portion of the casing for connectionwith said current carrying spring biasing means and means for theselective adjustment of the housing means and said casingV relative toeach other for adjustment of the pressure, required for operation of theswitch contacts. 5. In combination comprising, a portion having adiaphragm separatingtwo relatively shallow chambers formed therein andin which one chamber has a larger cross-section than the second chamber,separate passage means communieating with said chambers, a plunger ofsubstantially the same size as the second chamber and mountedformovement therein in 'response to pressure exerted on one side thereof bythe diabiasing means, means for associating the spring biasing meanswith the snap acting means, the

extending through the insulated portion of the casing for connectionwith said current carrying spring biasing means, an intermediate casingmember by which said portion is aligned and supported and upon which thesaid casing is threadedly secured for adjustment of the pressurerequired for operation of the switch contacts, said portion and saidcasing having external teeth extending axially of the switch, a sleevemember having internal teeth extending axially thereof for rigidlysecuring the sleeve member to said portion and casing to insureoperation of the switch in accordance with the selected adjustmentthereof.

6. A combination comprising, a switch controlling unit including mainswitching means, a relay for actuating the main switching means, asecond switching means for controlling the 'operation of the relay,means for actuating the second switching means for the actuation of therelay and main switching means, means for adjusting the second switchingmeans with respect to the actuating means therefor to selectively varythe operation of the relay and main switching means in response to theoperation of the said actuating means and terminal connector means forconnection with the main switching means.

7. The combination comprising, a switch con- 'y trolling deviceincluding a iirst switching means,l

a relay, device main switch controllingmeans actuated by the said relay,a casing for the said device and connector means extending through thesaid casing for connection with the said first switching means, therelay and the device main switch controlling means, condition responsivemeans for operating the said first switching means to actuate the relayfor control of the device main switch controlling means, the said casingincluding at least two sections threadedly secured with respect to eachother, and means for adjusting the operation of the first switchingmeans by the selective positioning of the said sections of the casing.

8. The combination comprising, a switch controlling device includingstationary and movable switch contact means, a relay, device main switchcontrolling means actuatedv by the said relay, a casing for the saiddevice and connector means extending through the said casing forconnection the pin to extend through the said passageway of the casingand sleeve.

9. In a unitary switch controlling device inl combination comprising,housing means for said device including a main portion, switching meansand condition responsive means for controlling the switching means inthe said main housing portion, a plurality of interchangeable coveringunits each including connector means insulatingly supported thereinconnected to said main portion of the housing means, the said coveringunits being adapted to include therein a relay and a main circuitswitching means, and the said main housing switching means beingoperable by the condition responsive `means for actuating the relay.

10. A condition responsive switch controlling device in combinationcomprising, a housing for said-device including a main portion, biasingmeans, snap acting switching means and condition responsive means foractuating a rst switching means located in said main housing portion, aplurality of interchangeable covering units, said covering units havingat least one switch connecting element supported therein and saidcovering units being adjustably mounted with respect to the main housingto cooperate with the said biasing means for adjustment of the operationof the device by the condition responsive means, said covering unitsbeing adaptedto include therein relay means and second switching means,and the first switching means is adapted to control the energization ofthe relay means whereby the relay means operates the second switchingmeans.

11. In a unitary switch controlling device in `combination comprising, ahousing for said device including a main portion, biasing means,

snap acting switching means and condition responsive means for actuatingfirst switching means located in said main housing portion, a pluralityof interchangeable covering units,- said covering units having at leastone switch connecting element supported therein and said covering unitsbeing adjustably mounted with respect to the main housing to cooperatewith the with the switch contact means, the relay and the I deviceswitch controlling means, condition responsive means for operating thevswitch contact means to control the operation of the device switchcontrolling means, the said casing including an intermediate and endportions threadedly 'secured with respect to each other, means foradjusting the operation of the device by these,-

lective positioning of the said end portions of the casing,'the saidparts of the casing having teeth on the outside thereof that extendvaxially of the device, 'a casing sleeve member having teeth thereinandextending axially thereof for cooperation with the said casing teeth toprevent relative movement between parts of the casing .and to maintainthe selected adjustmentv of the said device, a passageway extendingthrough the intermediate-portion of the casing and the said sleeve, anda locking pin with means forbiasing said biasing means for -adjustmentof the operation of the device by the condition responsive means, saidcovering units including therein mo- 4tor means and second switch meansoperated by y the said rst switching means, the motor means actuatingthe second switch means, the said main portion of the housing and thesaid covering units being threaded axially on outer portions thereof,and an .internally ,threaded sleeve member for cooperation with-the saidthreaded housing and covering units for locking them to a se'- lectedposition of adjustment for control by -the said condition responsivemeans. l l

12. A pressure actuated switching device in combination comprising, afirst portion including a base member having formed in a surface thereofa shallow chamber of relatively large cross-section, a passagewayextending through said base memberto said chamber, a housing memberhaving formed in a vsurface' thereof a chamber of relatively smallcross-section, a diaphragm supported between the members and separatingthe said chambers, a plunger member of substantially the size of saidsecond chamber and guided for slidable movement therein in respense tomovement of the said diaphragm, a

movable switch contact and stem means slidably actuated by the plungermember for actuation of the movable switch contact, astationary switchcontact in grounded contact with the said housing, a current carryingspring and movable contact biasing member, a spring guideand current linthe insulated portion of the casing member fo connection with the saidcurrent carrying movable contact switch biasing means. y

13. A pressure 'actuated switching device in combination comprising, aportion including a base member having formed in a surface thereof ashallow chamber of relatively large cross-section, a passagewayextending through said base member to said chamber, a housing memberhaving formed in a surface thereof a chamber of relatively small,cross-section, a diaphragm supported betweenl the members andseparating the said chambers, a plunger member of substan-= tially thesize of said second chamber and guided for slidable movement therein inresponse to movement of the said diaphragm, a movable switch contact,stem means slidably actuated by the plunger member for actuation of themovable switch contact, a stationary switch contact in grounded contactwith the said-housing, a current carrying spring for biasing the movablecontact member, a biasing spring guide and current carrying movablecontact actuating member, an upper casing member including an insulatingportion, switch connector means mounted in the insulated position of thecasing member for connection with said movable contact switch biasingmeans, a lowercasing member associated with said first portion, and anintermediate casing member, said member being threaded for extendingaxially thereof for cooperation with the casing members to maintain theswitch in the position of adjustment for operation at a selectedpressure.

15. A pressure actuated switching device in combination comprising, aportion including a base member having formed in a surface thereof ashallow chamber of relatively large cross-section, a passagewayextending through said base member to said chamber, a housing memberhaving formed in a surface thereof a chamber of reltact, a stationaryswitch contact in grounded contact with said housing, a current carryingspring the assembly of at least two of said casing members with respectto each other to provide for adjustment of the operation of the springbiasing means and the actuation of the switch con- Y tacts by thediaphragm at a selected pressure.

\ 14. A pressure actuated switching device in combination comprising, aportion including; a

base member having formed in a surface thereof and movable contactbiasing member, a spring guide and current carryingmovable contactactuating member, an rupper casing member including an insulatingportion, switch connector means mounted in the insulated portion of theupper casing member for connection with said movable contact switchbiasing means, a lower casing member associated with said first portionand an intermediate casing member, said member being threaded for theassembly of at least two of said casing members with respect to eachother to provide for adjustment of the operation of the spring biasingmeans and the actuation of the switch contacts by the diaphragm at aselected pressure, at least two of the casing members having axiallyVand outwardly extending teeth, a sleeve member having internal teethextending axially thereof for cooperation with the casing members tomain- 40 tain the switch at the position of adjustment for the lsizeof(said second chamber vand guided `vfor slidable movement therein inresponse to movement ofthe said diaphragm, a movable switch Y contact,stem means slidably actuated by the plunger member' for actuation of themovable switch contact, a stationary switch contact in grounded contactwith the said housing, a current carrying spring and movable contactbiasing member, a spring guide and current carrying movable contactactuating member, an upper casing member including an insulatingportion, switch connector` means mounted in the insulated portion of thecasing member for connection with saidmovable contact switch biasingmeans, a

lower casing member associated with said por-l tion, and an intermediatecasing member, said member being threaded for the assembly` of at leastvtwo-of saidcasing members with-respect to each other to provide foradjustment of the operation of the spring biasing means and the actu.-ation of the switch contacts by the diaphragm at a selected pressure, atleast two of the casing members having axially and outwardly extendingteeth, and a sleeve member having internal teeth operation at a selectedpressure, a passageway extending through the said sleeve member and thesaid housing, and a pin member biased to extend into the sleeve andhousing passageway for locking the switch 'in the position ofadjustment.

16. A switch` in combination comprising, casing means including separatecasing members, switching means, condition responsive means foractuating the switching means in a first manner, biasing means foropposing the operation of the switching meansjin-the nrst manner by thesaid condition responsive means, means for positioning said casingmembers to adjustl the biasing means ing members-and by said lockingmeans for radialv to control the operation of the switch by thecondition responsive means, a locking member, and axiallylextendingmeans carried by both said cascooperation to lock said casingmembers against relative rotation, whereby to maintain the switch in theselected position of adjustment for control lby the condition responsivemeans.

whereby to maintain the selected position of adjustment for operation ofthe switch.

18. A pressure switch in combination comprising, a base including apassage therethrough for the transmission of a uid pressure to a chamberformed in said member, a diaphragm for transmitting said fluid pressure,a plunger mounted for limited movement by said diaphragm in a chamberformed in a second member, a movable switch contact, a stationarycontact, means including said plunger for actuating the movable switchcontact, current carrying spring means for biasing the movable switchcontact actuating means in a manner to oppose the actuation of themovable switch contact actuating means by the transfer of pressure fromsaid diaphragm, a casing including at least one casing member adjustablysecured to a second casing member, the said adjustable casing membersproviding means for adjusting the said biasing means to operate the saidswitch at a predetermined'pressuie and having A switch connector meansfor connection with the rotatable members, said rotatable members beingin screw-threaded relation, whereby said rotation causes axial movementbetweensaid members, a locking member, axially extending means carriedby said members for radial cooperation to lock said members againstrelative rotation, whereby locking of said'rnenibers against rotation iseiective to fix the axial relationship between said'members, conditionresponsive apparatus associatedwth said members, the response of saidapparatus being adjustable by varying the axial brelationship between.said members, and releasable means positively maintaining said lockingmember in a selected axial position.

20. A plurality of axially adjacent relatively rotatable members, saidrotatable members being in screw-threaded relation, whereby saidrotation causes axial movements between said members, a locking member,external axially extending means carried by said rotatable members,internal axially extending means carried by said locking member forradial cooperation with said Ifirst mentioned means to lo'ck saidmembers against relative rotation, and condition responsive apparatusassociated with said members, said apparatus including adjustablebiasing means` for regulation of the response of said apparatus,"

said biasing means being adjustable by varying said axial relationshipbetween lvsaid members,

wherebyJ locking of said in eqx'nbers against rotation is electiveto fixthe axial distance between sabers, a locking member; internal axiallyextending teeth in said locking member for cooperation with said teethin said rotatable members to `lock said members against relativerotation, and

releasable means positively maintaining said locking member in aselected axial position, said last mentioned means comprising a groovein one of said members, alignable radial holes in said locking memberand one of said rotatable members, and a spring carried in said grooveand retractably passing through said holes.

22. In a control instrument, a plurality of axially adjacent relatively'rotatable members, said members being in screw-threaded relation,whereby said rotation causes axial movement between said members,axially extending teeth in a first of said members, axially extendingteeth in a second of said members, a locking member, axi- ,allyextending teeth in said locking member for cooperation with said teethin said rst and said second members whereby to lock said members againstrelative rotation, locking of said members against said rotation beingeffective to x the axial relationships between said members,

. condition responsive apparatus associated with said members, saidapparatus including adjustable biasing means for regulation of theresponse of said apparatus, said biasing means being adjustable byvarying the axial relationships be- `v and one of said rotatablemembers, and a spring carried in said groove and retractably passingthrough said holes.

23. In a control apparatus, a plurality'of axially adjacent rotatablemembers, a locking member, axially extending means carried by saidmembers for radial cooperation to lock said members against relativerotation, said rotatable members being in screw-threaded relation,whereby saidrotation causes axial movement between said members, andwhereby locking of said members against rotation is eective to fix theaxial relationships between said members, condition responsi'veapparatus associated with said members, the response of said apparatusbeing adjustable by varying the axial relationship between said members,and releasable means positively maintaining said locking member in aselected axial position, said last mentioned means comprising a groovein one of said members, alignable radial holes in said locking memberand one of said rotatable members, and a spring carried in said grooveand retractably passing through said holes.

As an article of manufacture, aa sub-assembly for a pressure actuatedswitch comprising a rst member having a passagewayicommuncating with'a'first pressure chamber of relative y large cross-section formed in oneend thereof, a second member having form'ed in one Y end thereof asecond pressure chamber of smaller plunger, a diaphragm separating thetwo saidv cross-section than the rst chamber, a plunger 'ofsubstantially the size of the said secondchamber and having a stemmounted for movement within the second member, passage 'means l throughsaid second member for communication with the second pressure chamberand including an qopening adjacent 'the inner side of'said pressurechambers, the depths of the chambers being such as to limit the movementof the stationary contact `having a passage for the transmission of afluid pressure to a chamber formed in said member, the said chamber, adiaphragm for transmitting said fluid pressure, a plunger mountedforlimited movement by said diaphragm in a chamber formed in a secondmember, a movable switch contact, a stationary contact, means includingsaid plunger for actuating the movable swit'ch contact, electricallyconducting spring means for biasing the movable switch contact actuatingmeans in a manner to oppose the actuation of the movable switch contactactuating means by the transfer of pressure from said diaphragm, and acasing member adapted 'to be connected with one of a plurality ofinterchangeable switch connector means, said casing member comprising agroove, a radial hole opening into said groove, and a spring retractablyprojecting through said hole, said casing member further comprisingaxially extending teeth for cooperation with similar teeth in a lockingmeans whereby to prevent relative rotation between said casing and saidlocking means.

26. A differential pressure responsive switch comprising a housingforming a pressure chamber, a high pressure bore and a low pressure borecommunicating with the chamber, a plunger slidably projecting into oneof said bores and hav'- ing a conical end portion .located in thechamber, a disk having a central depression rockingly engaging theconical end portion of said plunger, electrical contacts located in thechamber and insulated from the housing, and spring means viorbiasingthedisk towards the conical end of spring means for biasing the disktowards said conical end.

28. A pressure actuated switch device comprising an actuating mechanismincluding a base having a passage for the transmission of fluid pressureto a chamber formed in said member. the said chamber, a diaphragm fortransmitting said uid pressure, a plunger mounted for limited movementby said diaphragm in a chamber formed in a second member, a movableswitch contact, a stationary contact, means including said plunger foractuating the movable switch contact, electrically conducting springmeans for biasing the movable switch contact actuating means in a mannerto oppose the actuation of the movable switch contact actuating means bythe transfer of pressure from said diaphragm, a bellows enclosing andmaking electrical contact with said biasing spring, a iirst casingmember enclosing and supporting said actuating mechanism, said casingmember comprising a groove, a radial hole opening into said groove, anda spring retractably projecting through said hole, said casing memberfurther comprising axially extending teeth for cooperation with similarteeth in a locking means, whereby to prevent relative rotation betweensaid casing member and said locking means, and a second casing member,including an electrical connector.element, adapted to cooperate withsaid first casing member, said second casing member and said bellowsincluding coacting means telescopically making electrical contacttherebetween, whereby 'to complete an electric circuit from saidconnector element of said second casing member to one of said con- 29. Apressure responsive switch comprising a housing having an intermediateand end axial adjustable sections connected together forming a pressurechamber, a pressure bore communicating with the said chamber, pressureresponsive means operably mounted in said chamber, a stationary contactelectrically connected with vsaid housing, a movable contact actuated bysaid pressure responsive means, means for biasing the movable contact inopposition to the actuation of the pressure responsive means, bellowsmeans surrounding the biasing means, and at least two of the sections ofthe housing being axially adjusted to vary the values of the conditionactuating the pressure responsive means for operat- CERTIFICATE OFCORRECTION.

Patent No. 2,37'1,669. Marh 2o, 19m.

ALBERT E. BAAK.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 6,first oolimn, line 66, Claim 8, for "parts" read --end portions; andthat the said Letters Patent should be read with this correction thereinthat the same may conform to the record of the case in `the PatentOffice Signed and sealed this 18th day of September, A. D. 419MB.

Leslie Frazer (Seal) First Assistant Commissioner' of PatentsCERTIFICATE 0F CORRECTION. 4 Patent No. 2,57l,669. Marh 20, 1915.

ALBERT E.' BAAK.

It is herebyeertified that error' appears in the' printed specificationof the above numbered patent requiring correction as follows: Page 6,first eolnn, line 66, lClaim 8, forI "parte" read --end por'tions--gvand that the said Letters Patent should be resa with4 thiscorrection-*therein that the same may conform to the `record of the casein 'the Patent Office.

Signed and sealed this 18th day of' September, A. D.- {1.9LL5.

l l Leslie Frazer (seal) First Assistant comme;toner4 nf Patents.

